Adhesive with alkanoate blend

ABSTRACT

An adhesive composition includes 5 to 40% wt polyvinylpyrrolidone; 3 to 20% wt alkanoate blend including a first C n  carboxylic acid salt and a second C m  carboxylic acid salt, where n and m are integers in a range from 12 to 22; 20 to 60% wt of a water-soluble or water-dispersable solid material; 0.5 to 30 wt % of a liquid polyhydric alcohol; and 15 to 60% wt water. The adhesive composition can be clear and in glue stick form.

BACKGROUND

The present disclosure relates to adhesives that include an alkanoateblend. More specifically the present disclosure relates to adhesivesthat provide long-lasting initial tack, long open times, reducedsubstrate wrinkling, improved clarity, and/or reduced clumping.

Adhesives are known for the bonding of paper substrates, includingself-supporting solid adhesives as well as flowing liquid adhesives.Aqueous solid adhesives that include a fatty acid salt offer smooth,even application and good adhesive properties on paper, as disclosed inU.S. Pat. Nos. 3,576,776 and 6,066,689. Use of these soap-gel basedadhesives (“glue sticks”) has required quick closure of the bondingsurfaces immediately after applying the adhesive. Quick bond closure isnecessary because of the low initial adhesive tack which decreasesrapidly as the aqueous solvent evaporates. Moreover, despite apparentclaims to the contrary on commercial products, glue sticks have atendency to noticeably wrinkle paper substrates.

Liquid adhesives which bond paper are numerous. For consumer use, thebody of products containing an aqueous or water-miscible solvent isespecially attractive because of their decreased toxicity relative tovolatile, water-immiscible solvents. Frequently used adhesive polymersfor aqueous consumer adhesives include polyvinylalcohol (PVOH),polyvinylpyrrolidone (PVP), starches, poly(2-ethyl-2-oxazoline),cellulose, their copolymers and their derivatives.

The aqueous liquid and solid adhesives mentioned above suffer from oneor more of the following drawbacks: clumping; significant paperwrinkling; quickly deteriorating wet tack during application, short opentimes, temporary paper bonds.

SUMMARY

The present disclosure relates to adhesives that include an alkanoateblend. More specifically the present disclosure relates to adhesivesthat provide increased wet tack, long open times, reduced substratewrinkling, improved clarity, and/or reduced clumping as compared toadhesives, such as to glue sticks, that are commercially available.

One aspect relates to an adhesive composition that includes 5 to 40% wtpolyvinylpyrrolidone, 3 to 20% wt alkanoate blend of a first C_(n)carboxylic acid salt and a second C_(m) carboxylic acid salt, where nand m are integers in a range from 12 to 22, 20 to 60% wt of awater-soluble or water-dispersable material, 0.5 to 30 wt % of a liquidpolyhydric alcohol, and 15 to 60% wt water.

Another aspect relates to a clear adhesive composition that includes 5to 40% wt polyvinylpyrrolidone, 3 to 20% wt alkanoate blend of a firstC_(n) carboxylic acid salt and a second C_(m) carboxylic acid salt,where n and m are integers in a range from 12 to 22, 20 to 60% wt of awater-soluble or water-dispersable material, 0.5 to 30 wt % of a liquidpolyhydric alcohol, and 15 to 60% wt water. The clear adhesivecomposition has a visible wavelength light transmission in a range from90% to 100%.

A further aspect relates to a glue stick including 5 to 40% wtpolyvinylpyrrolidone, 3 to 20% wt alkanoate blend of a first C_(n)carboxylic acid salt and a second C_(m) carboxylic acid salt, where nand m are integers in a range from 12 to 22, 20 to 60% wt of awater-soluble or water-dispersable material, 0.5 to 30 wt % of a liquidpolyhydric alcohol, and 15 to 60% wt water.

In many embodiments, the total of the solid material, liquid polyhydricalcohol, and any other water-miscible solvent concentrations is at least50% of the total water content of the adhesive composition.

The above summary is not intended to describe each disclosed embodimentor every implementation of the present disclosure. The DetailedDescription and Examples that follow more particularly exemplify theseembodiments.

DETAILED DESCRIPTION

The present disclosure relates to adhesives that include an alkanoateblend. More specifically the present disclosure relates to adhesivesthat provide increased wet tack, long open times, reduced substratewrinkling, improved clarity, and/or reduced clumping.

For the following defined terms, these definitions shall be applied,unless a different definition is given in the claims or elsewhere inthis specification.

Weight percent, percent by weight, % by weight, % wt, and the like aresynonyms that refer to the concentration of a substance as the weight ofthat substance divided by the weight of the composition and multipliedby 100.

The recitation of numerical ranges by endpoints includes all numberssubsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3,3.80, 4, and 5).

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” include plural referents unless the contentclearly dictates otherwise. Thus, for example, reference to acomposition containing “a solid material” includes of two or more solidmaterials. As used in this specification and the appended claims, theterm “or” is generally employed in its sense including “and/or” unlessthe content clearly dictates otherwise.

Unless otherwise indicated, all numbers expressing quantities ofingredients, measurement of properties and so forth used in thespecification and claims are to be understood as being modified in allinstances by the term “about.” Accordingly, unless indicated to thecontrary, the numerical parameters set forth in the foregoingspecification and attached claims are approximations that can varydepending upon the desired properties sought to be obtained by thoseskilled in the art utilizing the teachings of the present invention. Atthe very least, and not as an attempt to limit the application of thedoctrine of equivalents to the scope of the claims, each numericalparameter should at least be construed in light of the number ofreported significant digits and by applying ordinary roundingtechniques. Notwithstanding that the numerical ranges and parameterssetting forth the broad scope of the invention are approximations, thenumerical values set forth in the specific examples are reported asprecisely as possible. Any numerical value, however, inherently containscertain errors necessarily resulting from the standard deviations foundin their respective testing measurements.

The present disclosure describes adhesives that can provide decreasedwrinkling when applied to paper substrates, increased wet tack, longopen times, reduced substrate wrinkling, improved clarity, and/orreduced clumping. The disclosed formulations can allow for a longerperiod of time between adhesive application and substrate bonding, yetproduce fiber tearing bonds instead of temporary adhesion. Theseattributes can be desirable for easy, permanent paper bonding andattractively bonded craft projects. These adhesives may also be usefulfor bonding non-paper substrates.

Increased wet-tack is achieved through use of any of a number ofwater-soluble or water-dispersible solids, among which water-solublecarbohydrates such as sucrose, carboxymethylcellulose, or starch andstarch derivatives are preferred. While not wishing to be bound by anyparticular theory, we believe the water-dispersible or water-solublesolids serve as tackifiers by increasing the elastic modulus ofinventive adhesive compositions at high deformation rates, whiledecreasing the elastic modulus at lower deformation rates. Thesesupposed changes in rheological behavior are in accord with an increasein the glass transition temperature and a decrease in the plateaumodulus of a pressure-sensitive adhesive.

Given an aqueous adhesive composition, one method of increasing the“open time”, i.e., the period over which the adhesive is aggressivelytacky and a successful bond can be made, is to simply increase theamount of water present in the adhesive. However, this adverselyincreases paper wrinkling as the adhesive material dries and shrinks.For glue sticks, shrinkage due to evaporation is especially undesirableduring consumer storage. In such cases, the result is a visibly deformedproduct which, although perhaps functional as an adhesive, is moredifficult to apply and aesthetically unappealing.

Another approach to improving open time is found in 3M's “restickable”glue stick (U.S. Pat. No. 5,409,977), which includes an inherently tackymicrosphere adhesive. After being applied and allowed to dry withoutbonding, this adhesive has sufficient tack to lightly bond substrates.However, this method of increasing open time may not be effective ifpermanent bonds are desired.

Improved open time is accomplished in the present invention throughcombined use of a water-soluble or water-dispersible solid material suchas sucrose, and liquid polyhydric alcohol such as 1,2 butanediol. Whilethe sucrose effectively increases adhesive wet tack, we have found thatusing both sucrose and liquid polyhydric alcohols promotes both high wettack and long open times.

Given an aqueous adhesive composition, one method of decreasingwrinkling during drying is to simply increase the adhesive polymerconcentration and reduce the solvent concentration. This results in lesswrinkling and a smaller volume change as the solvent evaporates, as wellas a shorter drying time. However, this approach also tends to result inincreased viscosity and manufacturing costs, and it can lead to a moremessy product use.

Another method of decreasing wrinkling during drying is to exchangewater for less volatile solvents such as C₃ and C₄ glycols and otherwater-miscible solvents. This approach also enhances the lubricity ofglue sticks to impart a smooth, gliding application. Using awater-miscible, slowly evaporating solvent allows for improved stressrelaxation during the drying process, such that less wrinkling occurswhile the adhesive shrinks. However, this approach can dramaticallyreduce adhesive tack while simultaneously slowing the drying process. Asa result bonded materials may need to be held in place or set aside fora lengthy period prior to use or display.

Adhesives described herein provide higher wet tack, longer-lasting tack(i.e., improved open time) and reduced paper wrinkling without thedrawbacks associated with methods described above. In particular,combined use of a water-soluble or water-dispersible solid with apolyhydric alcohol promotes strong initial tack, long open times andreduced substrate wrinkling. The adhesives offer immediate adhesion toarticles without undesirable pop-off or peeling and provide permanent,low-wrinkle bonds as the adhesive dries. By adjusting the adhesivecomposition, the adhesive may also be produced as a self-supporting gluestick, as described below.

The adhesive composition includes a water soluble adhesive resin orpolymer. In many embodiments, the water soluble adhesive resin orpolymer includes a polyvinylpyrrolidone (PVP), a polyvinyl alcohol(PVOH), poly(2)ethyl-2-oxazoline, water soluble starches, water solublestarch derivatives, and/or cellulose derivatives. Although PVP isexemplified throughout this specification, any one or more of the watersoluble adhesive resins or polymers can be utilized in addition to PVPor to replace PVP.

The adhesive composition includes polyvinylpyrrolidone, an alkanoateblend of a first C_(n) carboxylic acid salt and a second C_(m)carboxylic acid salt, where n and m are integers in a range from 12 to22, water, liquid polyhydric alcohol, and water-soluble orwater-dispersible solids. In some embodiments, the adhesive compositioncan be clear and in glue stick form.

In many embodiments, the adhesive composition includes 5 to 40% wtpolyvinylpyrrolidone, 3 to 20% wt alkanoate blend of a first C_(n)carboxylic acid salt and a second C_(m) carboxylic acid salt, where nand m are integers in a range from 12 to 22, liquid polyhydric alcohol,water-soluble or water-dispersible solids, and 15 to 60% wt water.

The alkanoate blend includes a mixture of at least two carboxylate saltshaving 12 to 22 carbon atoms and be either branched or straight chain,and may have one or more double bonds or one or more substituents suchas, for example, a halogen. The alkanoate blend can be used to improvemany features of the adhesive, whether to produce a liquid form withreduced sagging, or to produce a stick product having enhancedtranslucence and/or smoother application, for example. When the adhesiveis in the form of a glue stick it is desirable that the adhesive applyto an adherend in a smooth even layer. If the stick is not sufficientlyfirm, the adhesive fractures or breaks during application resulting indeposition of pieces of adhesive, i.e., “clumps” on the adherend ratherthan a smooth continuous adhesive film. This fracture and accompanyingdeposition of adhesive pieces during application is referred to as“clumping”.

While not wishing to be bound by any particular theory, we believe theenhanced translucence and reduced clumping of the inventive adhesivematerials containing an alkanoate blend results from accessing soap gelmicrostructures that feature amorphous association of hydrocarbonchains. Additionally, it has been found that introducing certain solidor liquid adjuvants to the adhesive having refractive indicescomplimentary to the soap gel microstucture can further improve gluestick translucency. These adjuvants may include polyhydric alcohols suchas sucrose, aliphatic glycols, etc.

Thus, adhesive compositions of the instant invention contain (1)alkanoate blends, which hinder ordering of aliphatic groups in the soapgel microstructure, and in some cases (2) solid materials having arefractive index sufficiently high to convey enhanced translucency tothe adhesive composition. Additionally these solid materials may alsoimpart enhanced tack and reduced wrinkling.

The alkanoate blend can be a salt derivative such as, for example,alkali metal, group II metal, group III metal, ammonium, and lower alkyl(C₁-C₄) ammonium salts of carboxylic acids. In many embodiments, thealkanoate blend includes C₁₂ to C₂₂ carboxylic acid sodium salts such assodium stearate, sodium oleate, sodium palmitate, sodium myristate, andsodium laurate which can yield particularly favorable results.

The first and second carboxylic acid salts can be in the alkanoate blendin any useful amounts. In many embodiments, the alkanoate blend is 5 to95 wt % first C_(n) carboxylic acid salt based on total weight ofalkanoate blend and 95 to 5 wt % second C_(m) carboxylic acid salt basedon total alkanoate blend, where n and m are integers in a range from 12to 18. In many embodiments, the alkanoate blend is 10 to 90 wt % firstC_(n) carboxylic acid salt based on total weight of alkanoate blend and90 to 10 wt % second C_(m) carboxylic acid salt based on total alkanoateblend, where n and m are integers in a range from 12 to 18. In someembodiments, the first and second carboxylic acid salts are each presentin the alkanoate blend in a range from 30 to 70% wt, based on the totalweight of alkanoate blend. In some embodiments, the first and secondcarboxylic acid salts are each present in the alkanoate blend in a rangefrom 40 to 60% wt, based on the total weight of alkanoate blend. In oneembodiment, the first and second carboxylic acid salts are each presentin the alkanoate blend in equal weight amounts. In illustrativeembodiments, the first carboxylic acid salt and the second carboxylicacid salt have carbon chain lengths that differ in length by two carbonatoms.

In some embodiments, the first C_(n) carboxylic acid salt is a C₁₂carboxylic acid salt (e.g., laurate salt) and the second C_(m)carboxylic acid salt is a C₁₄ carboxylic acid salt (e.g., myristatesalt). In some embodiments, the first C_(n) carboxylic acid salt is aC₁₄ carboxylic acid salt (e.g., myristate salt) and the second C_(m)carboxylic acid salt is a C₁₆ carboxylic acid salt (e.g., palmitatesalt). In other embodiments, the first C_(n) carboxylic acid salt is aC₁₆ carboxylic acid salt (e.g., palmitate salt) and the second C_(m)carboxylic acid salt is a C₁₈ carboxylic acid salt (e.g., stearatesalt).

In some embodiments, the alkanoate blend is a first C_(n) carboxylicacid salt, a second C_(m) carboxylic acid salt, and a third C_(b)carboxylic acid salt, where n, m and b are integers in a range from 12to 22. The first, second and third carboxylic acid salts can be in thealkanoate blend in any useful amounts. In some embodiments, the first,second and third carboxylic acid salts are each present in the alkanoateblend in a range from 20 to 40% wt, based on the total weight ofalkanoate blend. In one embodiment, the first, second and thirdcarboxylic acid salts are each present in the alkanoate blend in equalweight amounts.

In some embodiments, the first C_(n) carboxylic acid salt is a C₁₂carboxylic acid salt (e.g., laurate salt), the second C_(m) carboxylicacid salt is a C₁₄ carboxylic acid salt (e.g., myristate salt), and thethird C_(b) carboxylic acid salt is a C₁₆ carboxylic acid salt (e.g.,palmitate salt). In some embodiments, the first C_(n) carboxylic acidsalt is a C₁₄ carboxylic acid salt (e.g., myristate salt), the secondC_(m) carboxylic acid salt is a C₁₆ carboxylic acid salt (e.g.,palmitate salt), and the third C_(b) carboxylic acid salt is a C₁₈carboxylic acid salt (e.g., stearate salt). In other embodiments, thefirst C_(n) carboxylic acid salt is a C₁₆ carboxylic acid salt (e.g.,palmitate salt), the second C_(m) carboxylic acid salt is a C₁₈carboxylic acid salt (e.g., stearate salt), and the third C_(b)carboxylic acid salt is a C₂₀ carboxylic acid salt (e.g., arachidatesalt).

The adhesives include water, liquid polyhydric alcohols, and optionallyother water-miscible organic solvents in which the alkanoate blend,polyvinylpyrrolidone, and any other solid materials aredissolved/suspended. Among liquid polyhydric alcohols, any carbohydratehaving fewer than about 6 carbon atoms and a melting point below about70° F. may be used. Example liquid polyhydric alcohols include ethyleneglycol, propylene glycol, butylene glycol, and di- and tri-ethyleneglycol, glycerine and diglycerine. In many embodiments, liquidpolyhydric alcohols are present in the adhesive in a range of 0.5 to 30%wt or 5 to 20% wt, and water is present in the adhesive in a range of 15to 60% wt or 20 to 50% wt.

Other water misible organic solvents may optionally be used in theadhesive compositions. Examples include methanol, ethanol, andisopropanol; amyl alcohols, furfuryl alcohol, and benzyl alcohol as wellas dioxane, acetonitrile, tetrahydrofuran, dimethylformamide ordimethylsulfoxide can also be useful in small amounts. Moreover, acetoneand methylethylketone can also be suitable. Further, as water-miscibleorganic solvents, plasticizers and/or moisture retainers such as forinstance, tetraethyleneglycol, and lower molecular weight polyethyleneglycols can be employed. These auxiliary water-miscible organic solventsshould constitute 20% or less of the total adhesive composition.

A water soluble or water-dispersible solid material is included in theadhesives described herein. These water soluble or water-dispersiblesolid materials can increase adhesive setting time and decrease bondstrength at low deformation rates. The one or more water-soluble orwater dispersible solid materials increase the solid content of theadhesive compositions and serve as a tackifier for the adhesive polymer.These materials can be chosen in such a manner that the final adhesiveproduct has lasting initial tack, low wrinkling tendency, acceptablyswift setting speed, and improved clarity. In many embodiments, thesesolid materials are either crystalline materials with a melting pointabove 70° F. (21° C.), or viscoelastic fluids having a complex shearmodulus above about 200 Pa when measured at 70° F. (21° C.) and afrequency of 1 rad/s.

Water soluble or water-dispersible solid material can be dissolved ordispersed in submicron particle sizes in water at significantconcentrations (e.g., up to 10% by weight or higher). In manyembodiments, water soluble or water-dispersible solid materials arecompounds which significantly increase the solids concentration of theaqueous phase while minimally increasing its viscosity. Further, thesolid content of the adhesive composition should allow for reasonablyrapid solvent evaporation as the adhesive sets.

In many embodiments, water soluble or water-dispersible solid materialinclude crystalline sugars such as fructose, glucose, sucrose, sorbitol,mannitol, and xylitol, as well as their water-compatible esters. Inaddition, polymers of any molecular weight may also be used. In someembodiments, these polymers include polyesters, polyethers,polyacrylates, gelatin, polyacrylamides, their copolymers and theirderivatives. Inorganic materials such as fumed silica, colloidal silica,and alkali-halide salts may also be employed as water soluble orwater-dispersible solid materials. The array of materials which may beused as water-soluble or water-dispersible solids is broad and intendedto be understood as such. In many embodiments, the solid materialsshould be greater than about 19 to 20%, and less than about 60% to 50%by weight of the total adhesive composition. In some embodiments, thesolid material is present in the adhesive composition in a range from 20to 60%, or 20 to 50%, or 30 to 50% by weight of the total adhesivecomposition. In many embodiments, the ratio of the solid material to theadhesive polymer concentration (PVP) is between about 0.2:1.0 and about11.0:1.0. Further, in many embodiments the total of the solid material,liquid polyhydric alcohol, and other water-miscible solventconcentrations is at least 50% of the total water content of theadhesive composition.

In some embodiments, a clear adhesive composition includes 5 to 40% wtpolyvinylpyrrolidone, 3 to 20% wt alkanoate blend of a first C_(n)carboxylic acid salt and a second C_(m) carboxylic acid salt, where nand m are integers in a range from 12 to 22, 20 to 60% wt water solubleor water-dispersible solid material, 0.5 to 30% wt liquid polyhydricalcohol, and 15 to 60% wt water. These clear adhesive compositions canhave a visible wavelength light transmission in a range from 85% to 100%or from 90% to 100% at a selected visible light wavelength.

It is envisioned that the adhesive compositions of the present inventionmay also contain minor amounts of dyestuffs as well as pigments anddecorative materials. They may contain odor improving compounds such aspine-needle oil, eucalyptus oil, anise seed oil, benzaldehyde and thelike. Optionally, other additives may be added in minor amounts of lessthan about 10% to improve performance, stability, microbial resistance,appearance, pH control and other attributes.

The adhesive compositions can have any useful pH value. In manyembodiments, the adhesive composition has a pH value in a range from 6to 11, or 6 to 9, or 6 to 7.

The present invention should not be considered limited to the particularexamples described herein, but rather should be understood to cover allaspects of the invention as fairly set out in the attached claims.Various modifications, equivalent processes, as well as numerousstructures to which the present invention can be applicable will bereadily apparent to those of skill in the art to which the presentinvention is directed upon review of the instant specification.

EXAMPLES Test Methods

Adhesive Clarity Test

Visible wavelength light transmission measurement values are obtainedthrough adhesive samples having a thickness of 0.125 mm pressed between1 mm thick glass slides and at 21 degrees centigrade, using aspectrophotometer to record transmittance between 190 and 820 nmwavelengths, with a wavelength resolution of 2 nm.

Adhesive Clumping Test

Each adhesive was assigned a rating based on the amount of clumpingoccurring during application to paper. A common glue stick containerwith a rotary base was used to apply the adhesive with modest handpressure. Prior to applying the adhesive, a razor blade was used toslice away the open end of the adhesive sample, leaving a flat adhesivesurface. Samples which demonstrated an appreciable tendency to depositfractured clumps of adhesive gel during use were rated “poor,” whilesamples which did not tend to deposit clumps were rated “good.”

Adhesive Wrinkling Test

Each adhesive was assigned a wrinkling rating based on the amount ofwrinkling caused when two sheets of plain 20 lb. copier paper wereadhered together. Distinctions between the ratings “good,” and “poor”are readily noticeable to the unaided eye.

Adhesive Tack Test

This test provides a means of determining the tack exhibited byadhesives immediately after applying to a sheet of paper.

Adhesive is applied to a paper strip by mounting a gluestick in afixture on an Instrumentors, Inc., Model 3M90 Slip/Peel Tester, andoperating the peel tester to convey the paper strip past the gluestick.The adhesive-coated paper strip is then contacted with a cylindricalmandrel, the mandrel is elevated and the length of time the paperremains adhered to the mandrel recorded.

More specifically, an adhesive stick is mounted in a verticalorientation with the adhesive end of the stick oriented downward in anannular mounting fixture such that the adhesive end of the stick restson a 3.8 cm×28 cm strip of copy paper (Hammermill Copy Plus 20 lb, 84brightness) that has been affixed to the tester platen with a strip ofScotch 811 Removable Magic Tape. A 0.68 kg annular weight is placed atopthe annular mounting fixture securing the adhesive stick, and the peeltester is operated at a speed of 229 cm/minute to convey the paper stripbeneath the adhesive stick, thereby applying a continuous streak ofadhesive to the paper strip. This operation is repeated a second time onthe same sheet of paper to provide more complete adhesive coverage.Immediately following the second adhesive application, the tape stripadhering the paper to the platen is removed and an aluminum cylindermeasuring 12.8 mm dia×55.5 mm length and having a weight of 19.4 g isplaced on the adhesive stripe about 7 cm from the end of the paper stripand allowed to dwell for 2 seconds before the cylindrical weight islifted normal to the platen at a rate of 305 cm/minute a total distanceof 38 cm. The cylindrical element is maintained in this position amaximum time of 300 seconds or until the paper strip falls off thecylinder. The time at which the paper falls is noted and recorded. Thetest is repeated in its entirety 2 more times and the 3 values obtainedaveraged together and recorded as the Average Tack Time. Samples withinsufficient tack to completely lift the paper strip were recorded ashaving zero tack time.

Adhesive Open Time

This test provides a means of assessing the open time of an adhesive,i.e., the period over which the adhesive is aggressively tacky and asuccessful bond can be made. To perform this test, an adhesive isapplied to paper and five minutes are allowed to elapse prior tolaminating with a second sheet of paper. If a fiber-tearing bond wasformed within five minutes after the second sheet is laminated, theadhesive was said to have an open time of at least five minutes.

More specifically, a strip of plain 20 lb. copier paper was coated twicewith adhesive as described in the “adhesive tack test” above. After fiveminutes of exposure to ambient conditions (21° C., 50% relativehumidity), a second strip of plain copier paper was laminated to thecoated piece of paper using two gentle passes with a 2.8 kg roller.After five additional minutes of exposure to ambient conditions, thepieces of paper were delaminated swiftly by hand. If a fiber-tearingbond had formed between the paper strips, the adhesive was said to havean open time of more than five minutes. If no fiber-tearing bond wasproduced, the adhesive was said to have an open time of less than 5minutes.Sample Preparation

Each of the illustrative examples was prepared in a 1000 mL resin flaskequipped with a stirring motor and heated bath. Samples were heated totemperatures of 60° to 80° C. After a homogenous mixture was formed,bubbles were removed by applying aspirator vacuum for a period of 30 to60 seconds and the resulting sample was poured into a container andallowed to cool before use. In each of the examples below, the mold usedfor cooling was a common glue stick container, having an inside diameterof approximately 16 mm, with a rotary base driving a screw typeadvancing mechanism. Comparative product samples were used as provided.

Adhesive Compositions

The adhesive compositions (weight %) are described in Table Ia, TableIb, and Table Ic below:

TABLE Ia 1 2 3 4 5 6 Total water 15.0% 60.0% 38.5% 36.8% 38.0% 33.0% PVPK90 0.0% 15.0% 5.0% 0.0% 15.0% 11.0% PVP K30 15.0% 0.0% 0.0% 39.8% 0.0%0.0% PVOH 51-05 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% Sucrose 20.0% 20.0% 50.0%19.9% 20.0% 40.0% D-sorbitol 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%1,2-butanediol 0.0% 0.0% 0.0% 0.5% 10.0% 5.0% 1,2-propanediol 30.0% 2.0%0.5% 0.0% 10.0% 5.0% sodium myristate 10.0% 1.5% 3.0% 1.5% 2.3% 5.7%sodium palmitate 10.0% 1.5% 3.0% 1.5% 2.3% 0.3% Sodium Stearate 0.0%0.0% 0.0% 0.0% 2.3% 0.0%

TABLE Ib 7 8 9 10 Total water 58.9% 48.0% 33.0% 33.0% PVP K90 0.0% 11.0%10.0% 11.0% PVP K30 0.0% 0.0% 0.0% 0.0% PVOH 51-05 11.1% 0.0% 0.0% 0.0%Sucrose 22.2% 0.0% 41.0% 40.0% D-sorbitol 0.0% 30.0% 0.0% 0.0%1,2-butanediol 1.1% 5.0% 5.0% 5.0% 1,2-propanediol 0.0% 0.0% 5.0% 5.0%sodium myristate 3.3% 3.0% 3.0% 5.4% sodium palmitate 3.3% 3.0% 3.0%0.6% Sodium Stearate 0.0% 0.0% 0.0% 0.0%

TABLE Ic C1 C2 C3 C4 Total water 43.0% 73.0% 33.0% 83.0% PVP K90 11.0%11.0% 11.0% 11.0% PVP K30 0.0% 0.0% 0.0% 0.0% PVOH 51-05 0.0% 0.0% 0.0%0.0% Sucrose 40.0% 0.0% 40.0% 0.0% D-sorbitol 0.0% 0.0% 0.0% 0.0%1,2-butanediol 0.0% 5.0% 5.0% 0.0% 1,2-propanediol 0.0% 5.0% 5.0% 0.0%sodium myristate 3.0% 3.0% 6.0% 0.0% sodium palmitate 3.0% 3.0% 0.0%0.0% Sodium Stearate 0.0% 0.0% 0.0% 6.0%PVP K90 and K30 refers to polyvinylpyrrolidone and is available fromBASF Corporation, Mount Olive, N.J., or from International SpecialtyProducts GAF Corporation, Wayne, N.J., USA.PVOH 51-05 refers to Elvanol 51-05 partially hydrolyzed polyvinylalcoholavailable from Dupont Corporation, Wilmington, Del., USASurcose is available from Aldrich Corporation, St. Louis, Mo., USA1,2-butanediol is available from Aldrich Corporation, St. Louis, Mo.,USA1,2-propanediol is available from Aldrich Corporation, St. Louis, Mo.,USASodium myristate is available from Viva Corporation, Mumbai, IndiaSodium palmitate is available from Viva Corporation, Mumbai, IndiaSodium stearate is available from Viva Corporation, Mumbai, IndiaD-sorbitol is available from Aldrich Corporation, St. Louis, Mo., USA

Testing Results

Testing results of the Examples and comparative commercial adhesives arelisted in Table II below.

TABLE II Gelling agent blend ratio T_(650 nm) Tack hold WrinklingExample (C14:C16:C18) (%) Clumping Open Time time (sec) performance  11:1:0 33% poor less than 5 min. 0.0 Good  2 1:1:0 96% good less than 5min. 22.7 Poor  3 1:1:0 84% good less than 5 min. 0.0 Good  4 1:1:0 85%poor too soft too soft Poor  5 1:1:1 100%  good more than 5 min. 20.3Poor  6 95:5:0 84% good more than 5 min. 76.7 Good  7 1:1:0 17% poor toosoft too soft Poor  8 1:1:0 100%  good less than 5 min. 0.0 Poor  91:1:0 100%  good more than 5 min. 11.7 Good 10  90:10:0 92% good morethan 5 min. 47.3 Good C1 1:1:0 Produced foam during mixing - did nottest C2 1:1:0 88% good less than 5 min. 0.0 Poor C3 1:0:0 83% good morethan 5 min. 143.3 Good C4 0:0:1 25% poor less than 5 min. 0.0 Poor 3MScotch ™ — 33% poor less than 5 min. 3 Poor Glue Stick Elmer's all — 32%poor less than 5 min. 5 Poor Purpose glue stick Elmer's School — 19%poor less than 5 min. 5 Poor Glue Gel Glue Stick UHU ™ stic — 63% poorless than 5 min. 4 Poor3M Scotch® Glue Stick is available from 3M, St. Paul, Minn.Elmer's All-Purpose and School Glue Gel Glue Sticks are available fromElmer's Products, Inc., Columbus, Ohio.UHU™ stic is available from Saunders, Winthrop, Me.

All of the Examples and commercial adhesives can produce permanent,fiber-tearing paper bonds. However, the Examples are distinct inoffering increased wet tack, long open times, reduced substratewrinkling, improved clarity, and/or reduced clumping. For instance,although comparative example C3 affords long open times, reducedsubstrate wrinkling, and reduced clumping, the lack of a blended gellingagent minimizes clarity. In examples 6, 10, and 9, respectively, theincreasing ratio of C₁₆ to C₁₄ sodium alkanoates appears responsible forimproved clarity in the otherwise similar adhesives. Likewise,comparative example C2 has reduced clumping but poor wrinklingperformance, low tack hold time, and an open time of less than 5minutes. Example 9 (also see examples 6 & 10) has reduced wrinkling,higher tack hold time, and an open time of longer than 5 minutes,primarily because sucrose is incorporated in the composition at 40 wt %.

The present invention has been described with reference to severalembodiments thereof. The foregoing detailed description and exampleshave been provided for clarity of understanding only, and no unnecessarylimitations are to be understood therefrom. It will be apparent to thoseskilled in the art that many changes can be made to the describedembodiments without departing from the spirit and scope of theinvention. Thus, the scope of the invention should not be limited to theexact details of the compositions and structures described herein, butrather by the language of the claims that follow. In case of anyconflict, the present specification, including definitions, shallcontrol.

1. A glue stick consisting essentially of: 5 to 40% wt polyvinylpyrrolidone; 3 to 20% wt alkanoate blend comprising a first C_(n) carboxylic acid salt and a second C_(m) carboxylic acid salt, where n and m are different integers in a range from 12 to 22; 20 to 50% wt water soluble or water-dispersible solid material wherein the water-soluble or water dispersible solid material is sugar; 0.5 to 30% wt of a liquid polyhydric alcohol; and 15 to 60% wt water; wherein the total weight of the water-soluble or water-dispersible solid material and the liquid polyhydric alcohol is greater than 50% of the weight of the water and the adhesive composition has a visible wavelength light transmission in a range from 90% to 100%.
 2. An adhesive composition consisting essentially of: 5 to 40% wt polyvinylpyrrolidone; 3 to 20% wt alkanoate blend comprising a first C_(n) carboxylic acid salt and a second C_(m) carboxylic acid salt, where n and m are different integers in a range from 12 to 22; 20 to 50% wt of a water-soluble or water-dispersible solid material wherein the water-soluble or water dispersible solid material is sugar; 0.5 to 30% wt of a liquid polyhydric alcohol; 15 to 60% wt water; and wherein the total weight of the water-soluble or water-dispersible solid material and the liquid polyhydric alcohol is greater than 50% of the weight of the water and the adhesive composition has a visible wavelength light transmission in a range from 90% to 100%.
 3. The adhesive composition according to claim 2 wherein the adhesive composition further consisting essentially of 5 to 20% wt of said liquid polyhydric alcohol.
 4. The adhesive composition according to claim 2 wherein the alkanoate blend comprises 5 to 95% wt of the first C_(n) carboxylic acid salt based on total weight of alkanoate blend and 95 to 5% wt of the second C_(m) carboxylic acid salt based on total alkanoate blend, where n and m are integers in a range from 12 to
 18. 5. The adhesive composition according to claim 2 wherein the alkanoate blend comprises the first C_(n) carboxylic acid salt, the second C_(m) carboxylic acid salt, and a third C_(b) carboxylic acid salt, where n, m and b are different integers in a range from 12 to
 22. 6. The adhesive composition according to claim 2 wherein the alkanoate blend comprises 5 to 95% wt myristate salt based on total weight of alkanoate blend and 95 to 5% wt palmitate salt based on total alkanoate blend.
 7. The adhesive composition according to claim 2 wherein the alkanoate blend comprises 5 to 95% wt palmitate salt based on total weight of alkanoate blend and 95 to 5% wt stearate salt based on total alkanoate blend.
 8. The adhesive composition according to claim 2 wherein the alkanoate blend comprises 5 to 95% wt laurate salt based on total weight of alkanoate blend and 95 to 5% wt myristate salt based on total alkanoate blend.
 9. The adhesive composition according to claim 2, wherein the liquid polyhydric alcohol is one or more selected from the group consisting of 1,2-butanediol and 1,2-propanediol. 